We did an earlier look at this issue and now we can show more progress. So far 74 have been delivered. The table lists these along with the number of days from first flight to delivery. We list the number of tests flights for each delivery. On the whole, there has been progress. The only standout is, surprise, Qatar. But 2016 was a tough year, with lots of days being burned up even though test flights had declined.
If we look at customers with multiple deliveries over three years or more, we have three. The next charts list these and it seems, even with Qatar, Airbus has moved down the learning curve. There are fewer test flights and, generally, the number of days has also gone down. So Airbus is making progress on the program.
Addison, this website:
https://sites.google.com/site/a350xwbproduction/production-list
has data that refutes the assertion that the number of test flights for AY and VN has been reduced at all. In fact, the number of events in each year (particularly in 2017) for these three carriers is much too small to produce valid statistics to support your thesis of “progress.”